In recent years, a photosensitive resin composition containing an acid generating agent generating an acid upon irradiation of light is applied to various fields including a photoresist material and a photo curing material. An acid generated from an acid generating agent functions as a catalyst or a polymerization initiator.
In the case where the photosensitive resin composition is used as a photoresist material for forming a pattern, for example, an acid generating agent is irradiated with light to generate a strong acid. The strong acid generated from the acid generating agent functions as a catalyst and chemically modifies the resin component. The resin component is changed in solubility through chemical modification to form a pattern.
Various kinds of photoresist materials have been developed, and the photoresist materials are demanded to have high resolution and high sensitivity. The photoresist materials are also demanded to be capable of forming a pattern having high etching resistance. In particular, a material capable of forming a pattern having resistance to oxygen plasma etching is demanded as a deep ultraviolet ray resist material.
Various attempts for increasing a curing rate of a monomer, an oligomer, a polymer and the like have been made. The system that has been targeted for the development most frequently is a radical polymerization system, in which a radical species generated upon irradiation light is used as an initiator to polymerize numerous vinyl monomers in chains. A cationic polymerization system using an acid generated upon irradiation of light as a catalyst is also targeted for the development.
In the case of a radical polymerization system, the polymerization reaction is inhibited with oxygen in the air to decrease particularly the curing rate upon forming a thin film pattern, and therefore, it is necessary to block oxygen upon polymerization reaction. A cationic polymerization system has such an advantage that the polymerization reaction is not inhibited with oxygen in the air. However, an acid remains after curing to bring about a possibility of causing corrosion or degradation of the resin due to the acid.
Under the circumstances, such a photosensitive resin composition is strongly demanded that has high resolution and high sensitivity, is capable of forming a pattern having high etching resistance, is not inhibited in polymerization reaction with oxygen in the air, and does not generate a corrosive substance, such as a strong acid.
As a measure capable of attaining the demands, use of polymerization reaction or chemical reaction with a basic catalyst is proposed. Examples thereof include a method of using a base generating agent forming a base upon application of heat and chemically modifying a resin component with the base generated from the base generating agent as a catalyst.
An epoxy compound having an epoxy group undergoes crosslinking reaction by action of a base to be cured. Accordingly, for example, a base generating agent is irradiated with light or applied with heat to generate an amine compound in a layer containing an epoxy compound, whereby the epoxy compound can be cured by action of the amine compound as an initiator or a catalyst. However, even in the case where an amine compound is used as an initiator or a catalyst, the curing rate of the epoxy compound is low. In order to cure an epoxy compound sufficiently, a prolonged period of time is required, and it is necessary to carry out the heat treatment at a high temperature for increasing the curing rate, whereby the method has not yet been subjected to practical use.
Non-patent Document 1 shown below discloses base multiplying reaction capable of secondarily multiplying a basic compound generated by action of light. Patent Document 1 and Patent Document 2 shown below disclose a photosensitive composition containing a base multiplying agent, which is a urethane compound undergoing base multiplying reaction.
Patent Document 1: JP-A-2000-330270
Patent Document 2: JP-A-2002-128750
Non-patent Document 1: M. Miyamoto, K. Arimitsu and K. Ichimura, J. Photopolym. Sci. Technol., 12, 315 (1999), K. Arimitsu, M. Miyamoto and K. Ichimura, J. Photopolym. Sci. Technol., 12, 317 (1999), K. Arimitsu, M. Miyamoto and K. Ichimura, Angew. Chem., Int. Ed., 39, 3425 (2000)